There are known cruise control systems including a vehicle controller that controls vehicle speed on the basis of road information obtained from a navigation device and on the inter-vehicle distance to a preceding vehicle so that a vehicle can travel on the curve ahead at an appropriate speed. One such system is taught in Japanese Kokai Patent Application No. 2002-123898. In that vehicle controller, when there is a preceding vehicle, the target vehicle speed determined by the vehicle speed controller for traveling on the upcoming curve at an appropriate speed and the target vehicle speed determined by the vehicle speed controller corresponding to the inter-vehicle distance to the preceding vehicle are compared. The lower target vehicle speed is used as the speed instruction value sent to the actuator.